Hi Ben,

On 24/07/2025 15:13, Ben Horgan wrote:

On 11/07/2025 19:36, James Morse wrote:

quoted

Because an MSC can only by accessed from the CPUs in its cpu-affinity
set we need to be running on one of those CPUs to probe the MSC
hardware.

Do this work in the cpuhp callback. Probing the hardware will only
happen before MPAM is enabled, walk all the MSCs and probe those we can
reach that haven't already been probed.

Later once MPAM is enabled, this cpuhp callback will be replaced by
one that avoids the global list.

Enabling a static key will also take the cpuhp lock, so can't be done
from the cpuhp callback. Whenever a new MSC has been probed schedule
work to test if all the MSCs have now been probed.

quoted

diff --git a/drivers/platform/arm64/mpam/mpam_devices.c b/drivers/platform/arm64/mpam/

mpam_devices.c
index 0d6d5180903b..89434ae3efa6 100644

--- a/drivers/platform/arm64/mpam/mpam_devices.c
+++ b/drivers/platform/arm64/mpam/mpam_devices.c

@@ -513,9 +541,84 @@ int mpam_ris_create(struct mpam_msc *msc, u8 ris_idx,

      return err;
  }
  -static void mpam_discovery_complete(void)
+static int mpam_msc_hw_probe(struct mpam_msc *msc)
  {
-    pr_err("Discovered all MSC\n");
+    u64 idr;
+    int err;
+
+    lockdep_assert_held(&msc->probe_lock);
+
+    mutex_lock(&msc->part_sel_lock);
+    idr = mpam_read_partsel_reg(msc, AIDR);
+    if ((idr & MPAMF_AIDR_ARCH_MAJOR_REV) != MPAM_ARCHITECTURE_V1) {
+        pr_err_once("%s does not match MPAM architecture v1.0\n",
+                dev_name(&msc->pdev->dev));

The error message need only mention the major revision. You've added support for v1.1 and
v1.0.

Makes sense,


Thanks,

James